This invention relates to a packaging method, and particularly relates to a packaging method for organic polymer electroluminescent (EL) displays.
The conjugated polymer poly(P-phenylene vinylene), or PPV, was first coated on the single layer EL device as a luminant layer by Cambridge University (UK) in 1990. The PPV and its derivatives were widely used to make organic polymer EL displays because the properties of these polymers are similar to semiconductors and easily processed.
The basic structure of the organic polymer EL display comprises an anode consisting of a transparent electrode, a cathode consisting of a metallic electrode, and an organic polymer EL layer sandwiched between the anode and the cathode. When forward bias is applied, the electrons injected by the cathode and the holes injected by the anode will recombine within the organic polymer luminant layer. Subsequently, excitons are formed. Photons are emitting when excitons decay to the ground state.
However, with increasing demands for luminance, the operating stability and the durability of the device must be improved. For example, the degeneration of the cathode is caused by oxidation or reacting to the moisture in the air. The luminance is also decreased because of the degradation of the organic polymer luminant layer. Therefore, when the cathode of the traditional EL display is formed, an extra packaging process is required to passivate the cathode and the organic polymer luminant layer and prevent the oxygen and moisture from affecting the cathode and the organic polymer ruminant layer; thereby, the oxidation or corrosion can be avoided.
The traditional packaging processes for organic polymer EL display are illustrated in FIG. 1A to FIG. 1D.
First, referring to FIG. 1A, an ITO glass 10 is provided. Then the ITO glass 10 is patterned into a plurality of blocks 12 as anodes of organic polymer EL display by means of photolithography and etching.
Next, referring to FIG. 1B, the luminant PPV is coated on the top of the ITO pattern 12 to form an organic polymer luminescent layer 14. Then, Al electrodes 16 are formed on the top of the organic polymer layer 14 as cathode of the organic polymer EL display, and an organic polymer EL display 100 is generated.
Next, referring to FIGS. 1C and 1D, a sealing glass 20 coated with epoxide resin 18 is provided. Finally, the organic polymer EL display 100 is packaged by joining with the sealing glass 20 as shown in FIG. 1D.
However, the organic polymer layer 14 is directly contacted with epoxide resin 18, which may cause the degradation phenomena. Moreover, the formation of Al electrodes 16 and the epoxy packaging method are two independent process. Therefore this traditional packaging method is not suitable for mass-production.
In order to address the drawbacks of the conventional packaging method for organic polymer EL displays described above, this invention discloses a novel packaging method for organic polymer EL displays.
One feature of the present invention is to provide a packaging method for organic polymer EL displays, the steps comprising: (1) providing a glass substrate with an EL display device formed thereon, comprises a transparent electrode used as an anode on the glass substrate, an organic polymer layer coated on the top of the anode, and a metallic electrode used as a cathode formed on the top of the organic polymer layer; (2) forming a heat-dissipating layer to cover the cathode and the organic polymer layer; and (3) providing a packaging shell with a plurality of grids set inside, and sealing the heat-dissipating layer under N2.
In the packaging method described above, the transparent electrode consists of ITO. The organic polymer consists of organic luminant polymer materials, such as PPV or related series. The metallic electrode consists of electron-injecting materials, such as Al. The heat-dissipating layer consists of an insulator with high thermal conductivity, such as sputtered AlNx. The packaging shell consists of metals with high thermal conductivity, such as Cu. In addition, the sealing step is performed by using an agglutinant, such as epoxide, to fix the packaging shell on the top of the heat-dissipating layer.
Another feature of this invention is to provide a packaging method for organic polymer EL displays, the steps comprising: (1) providing a glass substrate with an EL display device formed thereon, comprises a transparent electrode used as an anode on the glass substrate, an organic polymer layer coated on the top of the anode, and a metallic electrode used as a cathode formed on the top of the organic polymer layer; (2) forming a heat-dissipating layer to cover the cathode and the organic polymer layer; and (3) forming a covering layer on the top of the heat-dissipating layer.
In the packaging method described above, the transparent electrode consists of ITO. The organic polymer consists of organic luminant polymer materials, such as PPV or related series. The metallic electrode consists of electron-injecting materials, such as Al. The heat-dissipating layer consists of an insulator with high thermal conductivity, such as sputtered AlNx. The covering layer consists of metals with high thermal conductivity, such as Cu.
Other feature and advantages of the invention will be apparent from the following detailed description, and from the claims.